With an increase in the amount of data handled by an electronic device, a library device that is provided with a storage rack in which a plurality of slots are provided and stores a large number of storage media such as magnetic tape cartridges, disk cartridges, and so forth is used. Such a library device includes one or a plurality of tape drives that read data from and write data into the storage media and a robot that moves the storage medium between the slot and the tape drive. The robot also moves the storage medium between a charge and discharge section, such as a mailslot, for a storage medium and the slot. The library device is used by being coupled to a plurality of servers. In such a library device, when job instructions are issued from the plurality of servers, the robot transports a large number of storage media. When the number of storage media to be transported is increased, the operating time of the robot is prolonged, and it may take time to complete the job.
Related art is disclosed in Japanese Laid-open Patent Publication No. 63-187456 or Japanese Laid-open Patent Publication No. 1-319164.